I have tried some techniques to resolve some media loading problems. The lessons learned were: References:
Network setup for KVM-QEMU
Qemu is a virtualization tool to virtualize IO including disk, network adapters. Typically, it supports 4 network models: Isolated, NAT, bridge and routing. Some materials can be found as follows:
Microsoft Edge Kiosk Mode /w Session Storage
What’s kiosk mode? If you go to fast food market, you may use vendor machine/self-assist machine to complete your shopping tasks. The applications in the modern operating systems we called kiosk. [1] Kiosk mode in MS edge The tutorials posted by Microsoft were for in private mode, which cannot retain users’ session data (e.g. IndexDB, […]
A c# implementation of Websocket: Websocket-sharp
If you are finding a websocket library which completely implement Websocket protocol RFC 6455)[1]. I would like to introduce WebsocketSharp. [2] Performance tips Although there is no size implementation for websocket, the limitations of websocket implementations are different. The original websocketsharp’s text buffer(initial frame size) is 1016 characters. If you want to increase the suze, […]
Image rendering and scaling algorithms in browsers
Image rendering control We can control the image rendering algorithms by setting image-rendering property in CSS. [1] What resize or image generation algorithms are in browser? If you’re interested in how chromium based browsers generate the images per size or quality parameters, you can refer to the source codes used in the project. [2] References
Blog has been migrated!
The original blog has been migrated to WordPress! 新站開張！我原本的Blog已經搬到這邊啦！
Logistics regression in Chinese
Here are recommended posts in Chinese for understanding logistics regressions. The readers can read them step by step. 1. 機器/統計學習: 羅吉斯回歸(Logistic regression), URL: https://chih-sheng-huang821.medium.com/%E6%A9%9F%E5%99%A8-%E7%B5%B1%E8%A8%88%E5%AD%B8%E7%BF%92-%E7%BE%85%E5%90%89%E6%96%AF%E5%9B%9E%E6%AD%B8-logistic-regression-aff7a830fb5d 2. 你可能不知道的邏輯回歸(Logistics Regression), URL: https://taweihuang.hpd.io/2017/12/22/logreg101/
科技的進步，學無止境
在2006年左右，我還在唸嘉義大學數學系時，跟同學分工合作，用PHP 5+Dreamweaver 寫學校處室網站，那時候學校IT不給MySQL/Sql Server，我自己還默默用很簡單的檔案系統處理函數，定義好資料結構，一行一行把「最新消息」等訊息，存在單一檔案作為offline database使用（那時候學藝不精，不知道有Sqlite可以用）。就這樣把學校處室的消息發布功能做了出來，還具備CRUD功能。 在那個大學年代，身兼學校的BBS系統站長，在那邊辛苦學習FreeBSD , Linux⋯當起MIS，三不五時就是去修伺服器，怎麼用fsck修硬碟, Make tools, build kernel 還自己去學怎麼剪RJ 45網路線，讓Server可以正常運作（可見那時候多窮，還要自己剪網路線）。 就這樣懵懵懂懂地大學畢業。 碩士班時期，實驗室還沒有積累一些關於data mining智慧資產，自己寫了一些演算法，像是PrefixSpan sequential pattern mining. 為了求效能，還全部用C++搭配STL寫。自己排crontab job，搭配bash script來產生自己要的實驗記錄。 博士班時期，老實說蠻精彩的。 當了三年的兼任助理，幫忙編hadoop教材…。為了自己的生計，還幫學校處室架設Wordpress，改別人的theme，甚至去看wordpress template怎麼寫，修掉別人模板的bug。也稍微懂得怎麼調整Apache的參數讓系統效能能夠跟得上來。 因為過去都用PHP寫網站，也順便接了幾個案子，像是做一些報名系統，多語系網站建置。 去當了幾家公司的兼任工程師，都是以C# + ASP.Net/MVC 作為主要工作技能。 曾經接了某個專利事務所的案子，幫別人寫Chrome外掛（後續做得不錯，顧客還有回鍋要我再幫忙開發，但是要顧學業，就婉拒了。） 曾幫博弈平台公司維護模組（這期間眼睛也去動手術了）。 為了打軟體競賽，還去用MongoDB，寫寫jQuery and Bootstrap。 為了做某公司的軟體專案，自己去玩Zebra ZPL印表機語言, WCF跟實作軟體序號與數位簽章演算法。 為了幫德國實驗室的同事做Big Data Benchmark，學怎麼用HBase & MapReduce API來做一些ETL工作（後來這也成為我的論文參考文獻之一）。 那時候政府還很流行Open Data，就去學架設CKAN，以及去研究HTTP協議，寫一些CKAN的prototype plugin。 出社會工作了，這些學到的技能也逐漸成為我的技術基石，不過是這些都是後話了。
Raspberry Pi Camera + OpenCV
If you are interested in how to use Raspberry Pi Camera + OpenCV to capture images, here is a great post in Chinese. https://link.medium.com/k2aEqonas8 However, the post had something wrong. If you want to install OpenCV packages of Python 3, please use the command “apt-get install python3-opencv”.
FFMPEG: Decode and then encode frames to JPEG images
I’ve used FFMPEG library for a while. Actually, the FFMPEG library’s decoding process flow can be described as the following picture. If you want to read the videos and then save to jpeg file, you can take a look on my programming code (tested on FFMPEG ver. 4 library). // VideoProcessing.cpp //#pragma onceusing namespace std;#include […]